NEW YORK — The pilots of a Delta plane that skidded off a runway at LaGuardia Airport last week during a snowstorm have told investigators that automatic systems designed to slow down the plane were not working properly, investigators said Monday.

The pilots said the plane’s automatic brakes were set to “max,” but they did not sense any deceleration as the aircraft veered toward Flushing Bay, according to the National Transportation Safety Board. The flight crew also said the runway appeared “all white” – covered in snow – when they broke out of the overcast sky and glimpsed it just moments before landing.

The plane’s automatic spoilers – flaps on top of the wings that reduce lift and slow the plane down – did not deploy, but the first officer deployed them manually. The captain also reported he was unable to prevent the airplane from drifting to the left.

Investigators said the plane was flying on autopilot until it was 230 feet off the ground, indicating a fairly routine landing until the very end.

Delta Flight 1086 from Atlanta was carrying 127 passengers, including two lap children, plus five crew members, when it slid off the runway Thursday and skidded about 2,000 feet along a normally grassy area alongside the runway that was covered in snow. For the last 940 of those feet, the plane’s left wing was cutting through and destroying the airport’s chain-link perimeter fence, investigators said. The aircraft came to rest with its nose leaning perilously on a berm that separates the runway from icy Flushing Bay.

The plane suffered damage to the left wing, including a punctured fuel tank that caused a leak. The belly of the aircraft from the nose to the first passenger door and the nose itself also were damaged, investigators said.